When you ponder it a little more than superficially, the phrase political correctness is a tautology. Thus the word “political,” by itself, already contains the sense of “correctness.” Deep down the two words mean “the same” (tauto in Greek). But let me extend this by looking at two words that seem to be related: political and polite. Political is rooted in the word “citizen,” polites in Latin; and that last word derives from polis, “city.” At this point “political” is not in any genuine sense equivalent to “correctness,” of course, but let us plow this furrow deeper. One idea might be to check if the words politic and polite both come from the same root; but that turns out to be wrong. Polite comes from the Latin politus; in spelling that word is almost identical to “citizen” (polites) but its meaning is “polished,” refined, hence elegant and accomplished. The word politic, however, despite its strong linkage to citizen in Latin, had acquired the meaning of “prudent, judicious,” by the 15th century, no doubt because a citizen must have those characteristics in order to get things done. In English, as well, we get the word “civil” from citizen; and civility relies on prudent and judicious behavior. Polite behavior, although derived from polishing rough things until they’re smooth, has functionally the same meaning. A polite person will always be politic, civil, thoughtful, and considerate. Tautology.
Now we could take this even further (always true where language is involved). The hardnosed critic of political correctness will point out that “correctness,” as used in that phrase, does not mean adherence to truth, necessarily; rather, it means obedience to a ideology, whether that ideology is true or not. And that’s also true. The phrase came into use for that reason, I think: to enforce an ideology. An alternative was already available when it was introduced: it was etiquette. Etiquette retains, to this day, the meaning of “correct behavior” whether in politics or other spheres of life.
Etiquette literally means a small slip of paper, a ticket, you might say. It comes from Old French estiquette, which simply meant a label. Etiquette, in the sense of “prescribed behavior” (notice behavior, not belief in anything) developed from “label” because people visiting courts (be they in France (étiquette), Italy (etichetta), or Spain (etiquette) were handed little cards on which the basic right behavior was printed to be learned. Similarly, soldiers assigned to be lodged in a village, temporarily, were issued a similar ticket with similar instructions on how to behave.
Etiquette is about such things as rising when a lady or elderly person needs a seat, which spoon to use, when to bow, when to speak, who goes first, what words may or may not be used (and here we are approaching but not reaching political correctness)—and never mind what you would rather do—like putting your muddy boots up on that beautifully laid Downton Abbey dinner table.
By combining “right behavior” with “prudent and judicious” speech, we might get political etiquette, a nice correction in the course on which we are now headed—a rough beaching on some arid sandbank or worse. No one possesses etiquette automatically; I remember my childhood. To do so you have to be brought up right. One has to have acquired manners—and education enough to understand the meaning of correct behavior until it becomes instinctive. And it doesn’t harm you if you read and study a fair amount to discover that you’re not born wise.
My source for etymologies and historical precedents comes, as always, from Oonline Etymology Dictionary (link).